Pattern inspection system

A system which inspects patternbearing material that is subject to topical distortions, comprising:

• means for scanning in a first direction a plurality of predefined local regions of a pattern to be inspected to provide an image of each local region, said means for scanning having a scan width, in a second direction, greater than the width in the second direction of each said local region and having an adjustable field of view for producing the image of each said local region;
• means for generating a reference image for each of said local regions;
• means for shifting the position of the image of each said local region to align as a pair the images in the second direction, said means for shifting including means for selecting within the scan width of said means for scanning the field of view utilized to produce the image of each said local region;
• and
• means for comparing each pair of aligned images to detect errors in the pattern independent of misalignment of and topical distortions of each said local region.

A system which inspects pattern-bearing material that is subject to topical distortions, comprising:

• means for scanning in a first direction a plurality of predefined local regions of a pattern to be inspected to provide an image of each local region;
• means for generating a reference image for each of said local regions;
• means for modifying in the first direction at least one of the dimension of the image of each said local region and the dimension of its corresponding reference image relative to each other to align as a pair the images in the first direction;
• and
• means for comparing each pair of aligned images to detect errors in the pattern independent of misalignment of and topical distortions of each said local region.

A method of inspecting pattern-bearing material that is subject to topical distortions, comprising:

• defining a plurality of local regions in a pattern to be inspected;
• scanning the pattern by passing in a first direction the local regions to provide an image of each local region, whereby the width of the scan in a second direction is greater than the width in the second direction of each local region;
• establishing within the scan width a field of view for producing the image of each local region;
• generating, for each local region, a reference image corresponding to that local region;
• determining for each set of corresponding images the difference in position of the local region relative to the portion of its corresponding reference image in a second direction;
• shifting the position of the image of each local region in the second direction to align the images in the second direction by adjusting the field of view utilized to produce the image of each local region;
• and
• comparing, for each local region, the aligned images to detect errors in the pattern independent of misalignment of and topical distortions of each said local region.

A method of inspecting pattern-bearing material that varies nonuniformly, comprising:

• defining a plurality of local regions in a pattern to be inspected;
• scanning the pattern by passing in a first direction the local regions to provide an image of each local region;
• generating, for each local region, a reference image corresponding to that local region;
• representing for each set of corresponding images the difference in position of the local region relative to the position of its reference image in the first direction;
• modifying in the first direction the dimension of the corresponding reference image relative to the image of that local region to align the images in the first direction;
• and
• comparing, for each local region, the aligned images to detect errors in the pattern independent of misalignment of and topical distortions of each said local region.